A power divider is widely used in order to distribute (divide) and/or synthesize a high frequency signal. As the construction of such a power divider represented by a plane circuit such as microstrip lines, there has been reported one in which a strip conductor is branched into two branch lines with a stub being formed at a branching portion (for example, see a first patent document).
The power divider described in this first patent document has an isolation circuit composed of an isolation resistance and a connecting line arranged between the two branch lines, and further has the stub with a open tip formed in the branching portion, whereby the parasitic reactance of the isolation circuit is offset or canceled by the stub, thus achieving a power divider of a good reflection property as seen from an input terminal.    First Patent Document: Japanese patent application laid-open No. H11-330813